Multiple Choice
Meiosis I produces _________ cells, and Meiosis II produces _________ cells.
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9. Mitosis and Meiosis
Meiosis
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During meiosis I in a human cell (2n = 46), how many DNA molecules will be present in each cell at the end of anaphase I?
A
23
B
69
C
46
D
92
Verified step by step guidance1
Recall that a human somatic cell is diploid with 2n = 46 chromosomes, meaning it has 46 chromosomes arranged in 23 homologous pairs.
Understand that before meiosis I begins, during the S phase of interphase, each chromosome is replicated, so each chromosome consists of two sister chromatids, which are considered two DNA molecules.
At the end of prophase I and metaphase I, the cell still has 46 chromosomes, but each chromosome is made up of two sister chromatids, so there are 92 DNA molecules in total.
During anaphase I, homologous chromosomes (each still consisting of two sister chromatids) are pulled to opposite poles, so each pole receives 23 chromosomes, each with two chromatids.
Therefore, at the end of anaphase I, each cell has 23 chromosomes, but since each chromosome consists of two sister chromatids, the number of DNA molecules in each cell is 23 multiplied by 2, which equals 46 DNA molecules per cell.
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